To improve suspension regenerative power with reasonable vehicle ride comfort,sensitivity analysis and optimization of hydraulic parameters to a hydraulic-electrical regenerative suspension were carried out. The regenerative suspension consists of a spring and a hydra-electrical regenerative unit. Based on the suspension structure and principle,a simulation model of the hydra-electrical regenerative unit was established by AMESim software. And the model was verified by a prototype testing of the hydraulic-electrical regenerative unit. Taking ISIGHT software as a platform,sensitivities of hydraulic system parameters affecting car-body vertical acceleration and suspension regenerative power were analyzed by a quarter car vehicle mode in AMESim. The results show that,compared with recharging pressures and volumes of two accumulators,hydraulic motor displacement has a significant effect on both the vehicle vertical acceleration and suspension regenerative power. Moreover,taking the vehicle vertical acceleration RMS value of a traditional suspension as a constraint,the hydraulic system parameters were optimized to maximize the suspension average regenerative power. The results show that the average regenerative power is improved by 12.7% after optimization when the vehicle ride comfort is acceptable.